/*
 *    Copyright 2009-2023 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       https://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.apache.ibatis.submitted.language;

import java.io.StringReader;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;

import org.apache.ibatis.builder.BuilderException;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.SqlSource;
import org.apache.ibatis.session.Configuration;
import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.RuntimeSingleton;
import org.apache.velocity.runtime.parser.node.SimpleNode;

/**
 * Just a test case. Not a real Velocity implementation.
 */
public class VelocitySqlSource implements SqlSource {

    public static final String PARAMETER_OBJECT_KEY = "_parameter";
    public static final String DATABASE_ID_KEY = "_databaseId";

    private final Configuration configuration;
    private final Template script;

    static {
        Velocity.setProperty("runtime.log", "target/velocity.log");
        Velocity.init();
    }

    public VelocitySqlSource(Configuration configuration, String scriptText) {
        this.configuration = configuration;
        try {
            RuntimeServices runtimeServices = RuntimeSingleton.getRuntimeServices();
            StringReader reader = new StringReader(scriptText);
            Template template = new Template();
            template.setName("Template name");
            SimpleNode node = runtimeServices.parse(reader, template);
            script = new Template();
            script.setRuntimeServices(runtimeServices);
            script.setData(node);
            script.initDocument();
        } catch (Exception ex) {
            throw new BuilderException("Error parsing velocity script", ex);
        }
    }

    @Override
    public BoundSql getBoundSql(Object parameterObject) {
        Map<String, Object> bindings = createBindings(parameterObject, configuration);
        VelocityContext context = new VelocityContext(bindings);
        StringWriter sw = new StringWriter();
        script.merge(context, sw);
        VelocitySqlSourceBuilder sqlSourceParser = new VelocitySqlSourceBuilder(configuration);
        Class<?> parameterType = parameterObject == null ? Object.class : parameterObject.getClass();
        SqlSource sqlSource = sqlSourceParser.parse(sw.toString(), parameterType);
        BoundSql boundSql = sqlSource.getBoundSql(parameterObject);
        for (Map.Entry<String, Object> entry : bindings.entrySet()) {
            boundSql.setAdditionalParameter(entry.getKey(), entry.getValue());
        }
        return boundSql;

    }

    public static Map<String, Object> createBindings(Object parameterObject, Configuration configuration) {
        Map<String, Object> bindings = new HashMap<>();
        bindings.put(PARAMETER_OBJECT_KEY, parameterObject);
        bindings.put(DATABASE_ID_KEY, configuration.getDatabaseId());
        bindings.put("it", new IteratorParameter(bindings));
        return bindings;
    }

    public static class IteratorParameter {

        private static final String PREFIX = "__frch_";
        private int count;
        private final Map<String, Object> bindings;

        public IteratorParameter(Map<String, Object> bindings) {
            this.bindings = bindings;
        }

        public String next(Object prop) {
            StringBuilder sb = new StringBuilder();
            String name = sb.append(PREFIX).append("_ITEM").append("_").append(count++).toString();
            bindings.put(name, prop);
            return name;
        }
    }
}
